The purpose of this proposal is to develop, validate and integrate novel biomarkers to characterize the risk of getting, having, or progressing with breast cancer. We have assembled a superb multidisciplinary team of academic and industry investigators who are using molecular and cell based technologies for biomarker development. We will further develop and evaluate them using powerful clinical resources, including unique retrospective and prospective data sets, and will integrate them with each other (cross validation) and into the context of clinical decision (modeling). The proposed studies attempt to redefine the paradigm from conventional breast cancer screening to combined detection/biological characterization/risk projection. Our hypotheses are that: 1) SNP (germline) and proteomic (serum) profiles can define breast cancer risk and detect early cancer, and may be combined for a tiered screening strategy;2) Promising biomarkers indicative of risk of progression and metastasis, including tissue-based expression profiling and detection of circulating tumor cells (CTCs), should be directly compared as well as integrated to maximize information about phenotypes and risk;and 3) Combined analysis of biomarkers is not only more efficient but may lead to integrated strategies for optimal clinical application. In order to accomplish our work we propose 4 projects: Project 1: Develop SNP- and serum proteomics-based profiles for cancer detection (primary and secondary) and risk profiling in the context of clinical evaluation of palpable and mammographic abnormalities; Project 2: Develop paraffin based expression profiles to predict risk of disease progression using retrospective datasets (Guy's Hospital: natural history population with 25 yr follow-up and no systemic therapy;UCSF comprehensive micrometastases/CTC data set;UCSF SPORE DCIS data set); Project 3: Develop and validate CTC-based assays, including leading approaches for CTC detection;cross-validate CTC data with tissue-based biomarkers;and develop methods for molecular profiling of CTCs; Project 4: Evaluate promising biomarkers in a prospective clinical study for cross validation of assays and integration into predictive outcome models that reflect the biological properties of the cancer detected.